#include <MsgBoxConstants.au3> ; to declare the Constants of MsgBox
Local $sRegex = "(?m)(.*Itemid=)(?!527)(\d*)"
Local $sString = "/docman/?view=document&alias=690-uchwala-rady-miasta-nr-xv-100-2015-zmieniajaca-uchwale-nr-xxxiii-151-2012&category_slug=gminne-programy-i-strategie&Itemid=123" & @CRLF & _
"/docman/?view=document&alias=690-uchwala-rady-miasta-nr-xv-100-2015-zmieniajaca-uchwale-nr-xxxiii-151-2012&category_slug=gminne-programy-i-strategie&Itemid=494" & @CRLF & _
"/docman/?view=document&alias=690-uchwala-rady-miasta-nr-xv-100-2015-zmieniajaca-uchwale-nr-xxxiii-151-2012&category_slug=gminne-programy-i-strategie&Itemid=527"
Local $sSubst = "${1}494"
Local $sResult = StringRegExpReplace($sString, $sRegex, $sSubst)
MsgBox($MB_SYSTEMMODAL, "Result", $sResult)
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for AutoIt, please visit: https://www.autoitscript.com/autoit3/docs/functions/StringRegExp.htm